diff options
Diffstat (limited to 'elf/dl-lookup.c')
| -rw-r--r-- | elf/dl-lookup.c | 1129 |
1 files changed, 0 insertions, 1129 deletions
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c deleted file mode 100644 index 3d2369dbf2..0000000000 --- a/elf/dl-lookup.c +++ /dev/null @@ -1,1129 +0,0 @@ -/* Look up a symbol in the loaded objects. - Copyright (C) 1995-2017 Free Software Foundation, Inc. - This file is part of the GNU C Library. - - The GNU C Library is free software; you can redistribute it and/or - modify it under the terms of the GNU Lesser General Public - License as published by the Free Software Foundation; either - version 2.1 of the License, or (at your option) any later version. - - The GNU C Library is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU - Lesser General Public License for more details. - - You should have received a copy of the GNU Lesser General Public - License along with the GNU C Library; if not, see - <http://www.gnu.org/licenses/>. */ - -#include <alloca.h> -#include <libintl.h> -#include <stdlib.h> -#include <string.h> -#include <unistd.h> -#include <ldsodefs.h> -#include <dl-hash.h> -#include <dl-machine.h> -#include <sysdep-cancel.h> -#include <libc-lock.h> -#include <tls.h> -#include <atomic.h> - -#include <assert.h> - -/* Return nonzero if check_match should consider SYM to fail to match a - symbol reference for some machine-specific reason. */ -#ifndef ELF_MACHINE_SYM_NO_MATCH -# define ELF_MACHINE_SYM_NO_MATCH(sym) 0 -#endif - -#define VERSTAG(tag) (DT_NUM + DT_THISPROCNUM + DT_VERSIONTAGIDX (tag)) - - -struct sym_val - { - const ElfW(Sym) *s; - struct link_map *m; - }; - - -#define make_string(string, rest...) \ - ({ \ - const char *all[] = { string, ## rest }; \ - size_t len, cnt; \ - char *result, *cp; \ - \ - len = 1; \ - for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt) \ - len += strlen (all[cnt]); \ - \ - cp = result = alloca (len); \ - for (cnt = 0; cnt < sizeof (all) / sizeof (all[0]); ++cnt) \ - cp = __stpcpy (cp, all[cnt]); \ - \ - result; \ - }) - -/* Statistics function. */ -#ifdef SHARED -# define bump_num_relocations() ++GL(dl_num_relocations) -#else -# define bump_num_relocations() ((void) 0) -#endif - -/* Utility function for do_lookup_x. The caller is called with undef_name, - ref, version, flags and type_class, and those are passed as the first - five arguments. The caller then computes sym, symidx, strtab, and map - and passes them as the next four arguments. Lastly the caller passes in - versioned_sym and num_versions which are modified by check_match during - the checking process. */ -static const ElfW(Sym) * -check_match (const char *const undef_name, - const ElfW(Sym) *const ref, - const struct r_found_version *const version, - const int flags, - const int type_class, - const ElfW(Sym) *const sym, - const Elf_Symndx symidx, - const char *const strtab, - const struct link_map *const map, - const ElfW(Sym) **const versioned_sym, - int *const num_versions) -{ - unsigned int stt = ELFW(ST_TYPE) (sym->st_info); - assert (ELF_RTYPE_CLASS_PLT == 1); - if (__glibc_unlikely ((sym->st_value == 0 /* No value. */ - && stt != STT_TLS) - || ELF_MACHINE_SYM_NO_MATCH (sym) - || (type_class & (sym->st_shndx == SHN_UNDEF)))) - return NULL; - - /* Ignore all but STT_NOTYPE, STT_OBJECT, STT_FUNC, - STT_COMMON, STT_TLS, and STT_GNU_IFUNC since these are no - code/data definitions. */ -#define ALLOWED_STT \ - ((1 << STT_NOTYPE) | (1 << STT_OBJECT) | (1 << STT_FUNC) \ - | (1 << STT_COMMON) | (1 << STT_TLS) | (1 << STT_GNU_IFUNC)) - if (__glibc_unlikely (((1 << stt) & ALLOWED_STT) == 0)) - return NULL; - - if (sym != ref && strcmp (strtab + sym->st_name, undef_name)) - /* Not the symbol we are looking for. */ - return NULL; - - const ElfW(Half) *verstab = map->l_versyms; - if (version != NULL) - { - if (__glibc_unlikely (verstab == NULL)) - { - /* We need a versioned symbol but haven't found any. If - this is the object which is referenced in the verneed - entry it is a bug in the library since a symbol must - not simply disappear. - - It would also be a bug in the object since it means that - the list of required versions is incomplete and so the - tests in dl-version.c haven't found a problem.*/ - assert (version->filename == NULL - || ! _dl_name_match_p (version->filename, map)); - - /* Otherwise we accept the symbol. */ - } - else - { - /* We can match the version information or use the - default one if it is not hidden. */ - ElfW(Half) ndx = verstab[symidx] & 0x7fff; - if ((map->l_versions[ndx].hash != version->hash - || strcmp (map->l_versions[ndx].name, version->name)) - && (version->hidden || map->l_versions[ndx].hash - || (verstab[symidx] & 0x8000))) - /* It's not the version we want. */ - return NULL; - } - } - else - { - /* No specific version is selected. There are two ways we - can got here: - - - a binary which does not include versioning information - is loaded - - - dlsym() instead of dlvsym() is used to get a symbol which - might exist in more than one form - - If the library does not provide symbol version information - there is no problem at all: we simply use the symbol if it - is defined. - - These two lookups need to be handled differently if the - library defines versions. In the case of the old - unversioned application the oldest (default) version - should be used. In case of a dlsym() call the latest and - public interface should be returned. */ - if (verstab != NULL) - { - if ((verstab[symidx] & 0x7fff) - >= ((flags & DL_LOOKUP_RETURN_NEWEST) ? 2 : 3)) - { - /* Don't accept hidden symbols. */ - if ((verstab[symidx] & 0x8000) == 0 - && (*num_versions)++ == 0) - /* No version so far. */ - *versioned_sym = sym; - - return NULL; - } - } - } - - /* There cannot be another entry for this symbol so stop here. */ - return sym; -} - -/* Utility function for do_lookup_unique. Add a symbol to TABLE. */ -static void -enter_unique_sym (struct unique_sym *table, size_t size, - unsigned int hash, const char *name, - const ElfW(Sym) *sym, const struct link_map *map) -{ - size_t idx = hash % size; - size_t hash2 = 1 + hash % (size - 2); - while (table[idx].name != NULL) - { - idx += hash2; - if (idx >= size) - idx -= size; - } - - table[idx].hashval = hash; - table[idx].name = name; - table[idx].sym = sym; - table[idx].map = map; -} - -/* Utility function for do_lookup_x. Lookup an STB_GNU_UNIQUE symbol - in the unique symbol table, creating a new entry if necessary. - Return the matching symbol in RESULT. */ -static void -do_lookup_unique (const char *undef_name, uint_fast32_t new_hash, - const struct link_map *map, struct sym_val *result, - int type_class, const ElfW(Sym) *sym, const char *strtab, - const ElfW(Sym) *ref, const struct link_map *undef_map) -{ - /* We have to determine whether we already found a symbol with this - name before. If not then we have to add it to the search table. - If we already found a definition we have to use it. */ - - struct unique_sym_table *tab - = &GL(dl_ns)[map->l_ns]._ns_unique_sym_table; - - __rtld_lock_lock_recursive (tab->lock); - - struct unique_sym *entries = tab->entries; - size_t size = tab->size; - if (entries != NULL) - { - size_t idx = new_hash % size; - size_t hash2 = 1 + new_hash % (size - 2); - while (1) - { - if (entries[idx].hashval == new_hash - && strcmp (entries[idx].name, undef_name) == 0) - { - if ((type_class & ELF_RTYPE_CLASS_COPY) != 0) - { - /* We possibly have to initialize the central - copy from the copy addressed through the - relocation. */ - result->s = sym; - result->m = (struct link_map *) map; - } - else - { - result->s = entries[idx].sym; - result->m = (struct link_map *) entries[idx].map; - } - __rtld_lock_unlock_recursive (tab->lock); - return; - } - - if (entries[idx].name == NULL) - break; - - idx += hash2; - if (idx >= size) - idx -= size; - } - - if (size * 3 <= tab->n_elements * 4) - { - /* Expand the table. */ -#ifdef RTLD_CHECK_FOREIGN_CALL - /* This must not happen during runtime relocations. */ - assert (!RTLD_CHECK_FOREIGN_CALL); -#endif - size_t newsize = _dl_higher_prime_number (size + 1); - struct unique_sym *newentries - = calloc (sizeof (struct unique_sym), newsize); - if (newentries == NULL) - { - nomem: - __rtld_lock_unlock_recursive (tab->lock); - _dl_fatal_printf ("out of memory\n"); - } - - for (idx = 0; idx < size; ++idx) - if (entries[idx].name != NULL) - enter_unique_sym (newentries, newsize, entries[idx].hashval, - entries[idx].name, entries[idx].sym, - entries[idx].map); - - tab->free (entries); - tab->size = newsize; - size = newsize; - entries = tab->entries = newentries; - tab->free = free; - } - } - else - { -#ifdef RTLD_CHECK_FOREIGN_CALL - /* This must not happen during runtime relocations. */ - assert (!RTLD_CHECK_FOREIGN_CALL); -#endif - -#ifdef SHARED - /* If tab->entries is NULL, but tab->size is not, it means - this is the second, conflict finding, lookup for - LD_TRACE_PRELINKING in _dl_debug_bindings. Don't - allocate anything and don't enter anything into the - hash table. */ - if (__glibc_unlikely (tab->size)) - { - assert (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK); - goto success; - } -#endif - -#define INITIAL_NUNIQUE_SYM_TABLE 31 - size = INITIAL_NUNIQUE_SYM_TABLE; - entries = calloc (sizeof (struct unique_sym), size); - if (entries == NULL) - goto nomem; - - tab->entries = entries; - tab->size = size; - tab->free = free; - } - - if ((type_class & ELF_RTYPE_CLASS_COPY) != 0) - enter_unique_sym (entries, size, new_hash, strtab + sym->st_name, ref, - undef_map); - else - { - enter_unique_sym (entries, size, - new_hash, strtab + sym->st_name, sym, map); - - if (map->l_type == lt_loaded) - /* Make sure we don't unload this object by - setting the appropriate flag. */ - ((struct link_map *) map)->l_flags_1 |= DF_1_NODELETE; - } - ++tab->n_elements; - -#ifdef SHARED - success: -#endif - __rtld_lock_unlock_recursive (tab->lock); - - result->s = sym; - result->m = (struct link_map *) map; -} - -/* Inner part of the lookup functions. We return a value > 0 if we - found the symbol, the value 0 if nothing is found and < 0 if - something bad happened. */ -static int -__attribute_noinline__ -do_lookup_x (const char *undef_name, uint_fast32_t new_hash, - unsigned long int *old_hash, const ElfW(Sym) *ref, - struct sym_val *result, struct r_scope_elem *scope, size_t i, - const struct r_found_version *const version, int flags, - struct link_map *skip, int type_class, struct link_map *undef_map) -{ - size_t n = scope->r_nlist; - /* Make sure we read the value before proceeding. Otherwise we - might use r_list pointing to the initial scope and r_nlist being - the value after a resize. That is the only path in dl-open.c not - protected by GSCOPE. A read barrier here might be to expensive. */ - __asm volatile ("" : "+r" (n), "+m" (scope->r_list)); - struct link_map **list = scope->r_list; - - do - { - const struct link_map *map = list[i]->l_real; - - /* Here come the extra test needed for `_dl_lookup_symbol_skip'. */ - if (map == skip) - continue; - - /* Don't search the executable when resolving a copy reloc. */ - if ((type_class & ELF_RTYPE_CLASS_COPY) && map->l_type == lt_executable) - continue; - - /* Do not look into objects which are going to be removed. */ - if (map->l_removed) - continue; - - /* Print some debugging info if wanted. */ - if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_SYMBOLS)) - _dl_debug_printf ("symbol=%s; lookup in file=%s [%lu]\n", - undef_name, DSO_FILENAME (map->l_name), - map->l_ns); - - /* If the hash table is empty there is nothing to do here. */ - if (map->l_nbuckets == 0) - continue; - - Elf_Symndx symidx; - int num_versions = 0; - const ElfW(Sym) *versioned_sym = NULL; - - /* The tables for this map. */ - const ElfW(Sym) *symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]); - const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]); - - const ElfW(Sym) *sym; - const ElfW(Addr) *bitmask = map->l_gnu_bitmask; - if (__glibc_likely (bitmask != NULL)) - { - ElfW(Addr) bitmask_word - = bitmask[(new_hash / __ELF_NATIVE_CLASS) - & map->l_gnu_bitmask_idxbits]; - - unsigned int hashbit1 = new_hash & (__ELF_NATIVE_CLASS - 1); - unsigned int hashbit2 = ((new_hash >> map->l_gnu_shift) - & (__ELF_NATIVE_CLASS - 1)); - - if (__glibc_unlikely ((bitmask_word >> hashbit1) - & (bitmask_word >> hashbit2) & 1)) - { - Elf32_Word bucket = map->l_gnu_buckets[new_hash - % map->l_nbuckets]; - if (bucket != 0) - { - const Elf32_Word *hasharr = &map->l_gnu_chain_zero[bucket]; - - do - if (((*hasharr ^ new_hash) >> 1) == 0) - { - symidx = hasharr - map->l_gnu_chain_zero; - sym = check_match (undef_name, ref, version, flags, - type_class, &symtab[symidx], symidx, - strtab, map, &versioned_sym, - &num_versions); - if (sym != NULL) - goto found_it; - } - while ((*hasharr++ & 1u) == 0); - } - } - /* No symbol found. */ - symidx = SHN_UNDEF; - } - else - { - if (*old_hash == 0xffffffff) - *old_hash = _dl_elf_hash (undef_name); - - /* Use the old SysV-style hash table. Search the appropriate - hash bucket in this object's symbol table for a definition - for the same symbol name. */ - for (symidx = map->l_buckets[*old_hash % map->l_nbuckets]; - symidx != STN_UNDEF; - symidx = map->l_chain[symidx]) - { - sym = check_match (undef_name, ref, version, flags, - type_class, &symtab[symidx], symidx, - strtab, map, &versioned_sym, - &num_versions); - if (sym != NULL) - goto found_it; - } - } - - /* If we have seen exactly one versioned symbol while we are - looking for an unversioned symbol and the version is not the - default version we still accept this symbol since there are - no possible ambiguities. */ - sym = num_versions == 1 ? versioned_sym : NULL; - - if (sym != NULL) - { - found_it: - /* When UNDEF_MAP is NULL, which indicates we are called from - do_lookup_x on relocation against protected data, we skip - the data definion in the executable from copy reloc. */ - if (ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA - && undef_map == NULL - && map->l_type == lt_executable - && type_class == ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA) - { - const ElfW(Sym) *s; - unsigned int i; - -#if ! ELF_MACHINE_NO_RELA - if (map->l_info[DT_RELA] != NULL - && map->l_info[DT_RELASZ] != NULL - && map->l_info[DT_RELASZ]->d_un.d_val != 0) - { - const ElfW(Rela) *rela - = (const ElfW(Rela) *) D_PTR (map, l_info[DT_RELA]); - unsigned int rela_count - = map->l_info[DT_RELASZ]->d_un.d_val / sizeof (*rela); - - for (i = 0; i < rela_count; i++, rela++) - if (elf_machine_type_class (ELFW(R_TYPE) (rela->r_info)) - == ELF_RTYPE_CLASS_COPY) - { - s = &symtab[ELFW(R_SYM) (rela->r_info)]; - if (!strcmp (strtab + s->st_name, undef_name)) - goto skip; - } - } -#endif -#if ! ELF_MACHINE_NO_REL - if (map->l_info[DT_REL] != NULL - && map->l_info[DT_RELSZ] != NULL - && map->l_info[DT_RELSZ]->d_un.d_val != 0) - { - const ElfW(Rel) *rel - = (const ElfW(Rel) *) D_PTR (map, l_info[DT_REL]); - unsigned int rel_count - = map->l_info[DT_RELSZ]->d_un.d_val / sizeof (*rel); - - for (i = 0; i < rel_count; i++, rel++) - if (elf_machine_type_class (ELFW(R_TYPE) (rel->r_info)) - == ELF_RTYPE_CLASS_COPY) - { - s = &symtab[ELFW(R_SYM) (rel->r_info)]; - if (!strcmp (strtab + s->st_name, undef_name)) - goto skip; - } - } -#endif - } - - /* Hidden and internal symbols are local, ignore them. */ - if (__glibc_unlikely (dl_symbol_visibility_binds_local_p (sym))) - goto skip; - - switch (ELFW(ST_BIND) (sym->st_info)) - { - case STB_WEAK: - /* Weak definition. Use this value if we don't find another. */ - if (__glibc_unlikely (GLRO(dl_dynamic_weak))) - { - if (! result->s) - { - result->s = sym; - result->m = (struct link_map *) map; - } - break; - } - /* FALLTHROUGH */ - case STB_GLOBAL: - /* Global definition. Just what we need. */ - result->s = sym; - result->m = (struct link_map *) map; - return 1; - - case STB_GNU_UNIQUE:; - do_lookup_unique (undef_name, new_hash, map, result, type_class, - sym, strtab, ref, undef_map); - return 1; - - default: - /* Local symbols are ignored. */ - break; - } - } - -skip: - /* If this current map is the one mentioned in the verneed entry - and we have not found a weak entry, it is a bug. */ - if (symidx == STN_UNDEF && version != NULL && version->filename != NULL - && __glibc_unlikely (_dl_name_match_p (version->filename, map))) - return -1; - } - while (++i < n); - - /* We have not found anything until now. */ - return 0; -} - - -static uint_fast32_t -dl_new_hash (const char *s) -{ - uint_fast32_t h = 5381; - for (unsigned char c = *s; c != '\0'; c = *++s) - h = h * 33 + c; - return h & 0xffffffff; -} - - -/* Add extra dependency on MAP to UNDEF_MAP. */ -static int -internal_function -add_dependency (struct link_map *undef_map, struct link_map *map, int flags) -{ - struct link_map *runp; - unsigned int i; - int result = 0; - - /* Avoid self-references and references to objects which cannot be - unloaded anyway. */ - if (undef_map == map) - return 0; - - /* Avoid references to objects which cannot be unloaded anyway. */ - assert (map->l_type == lt_loaded); - if ((map->l_flags_1 & DF_1_NODELETE) != 0) - return 0; - - struct link_map_reldeps *l_reldeps - = atomic_forced_read (undef_map->l_reldeps); - - /* Make sure l_reldeps is read before l_initfini. */ - atomic_read_barrier (); - - /* Determine whether UNDEF_MAP already has a reference to MAP. First - look in the normal dependencies. */ - struct link_map **l_initfini = atomic_forced_read (undef_map->l_initfini); - if (l_initfini != NULL) - { - for (i = 0; l_initfini[i] != NULL; ++i) - if (l_initfini[i] == map) - return 0; - } - - /* No normal dependency. See whether we already had to add it - to the special list of dynamic dependencies. */ - unsigned int l_reldepsact = 0; - if (l_reldeps != NULL) - { - struct link_map **list = &l_reldeps->list[0]; - l_reldepsact = l_reldeps->act; - for (i = 0; i < l_reldepsact; ++i) - if (list[i] == map) - return 0; - } - - /* Save serial number of the target MAP. */ - unsigned long long serial = map->l_serial; - - /* Make sure nobody can unload the object while we are at it. */ - if (__glibc_unlikely (flags & DL_LOOKUP_GSCOPE_LOCK)) - { - /* We can't just call __rtld_lock_lock_recursive (GL(dl_load_lock)) - here, that can result in ABBA deadlock. */ - THREAD_GSCOPE_RESET_FLAG (); - __rtld_lock_lock_recursive (GL(dl_load_lock)); - /* While MAP value won't change, after THREAD_GSCOPE_RESET_FLAG () - it can e.g. point to unallocated memory. So avoid the optimizer - treating the above read from MAP->l_serial as ensurance it - can safely dereference it. */ - map = atomic_forced_read (map); - - /* From this point on it is unsafe to dereference MAP, until it - has been found in one of the lists. */ - - /* Redo the l_initfini check in case undef_map's l_initfini - changed in the mean time. */ - if (undef_map->l_initfini != l_initfini - && undef_map->l_initfini != NULL) - { - l_initfini = undef_map->l_initfini; - for (i = 0; l_initfini[i] != NULL; ++i) - if (l_initfini[i] == map) - goto out_check; - } - - /* Redo the l_reldeps check if undef_map's l_reldeps changed in - the mean time. */ - if (undef_map->l_reldeps != NULL) - { - if (undef_map->l_reldeps != l_reldeps) - { - struct link_map **list = &undef_map->l_reldeps->list[0]; - l_reldepsact = undef_map->l_reldeps->act; - for (i = 0; i < l_reldepsact; ++i) - if (list[i] == map) - goto out_check; - } - else if (undef_map->l_reldeps->act > l_reldepsact) - { - struct link_map **list - = &undef_map->l_reldeps->list[0]; - i = l_reldepsact; - l_reldepsact = undef_map->l_reldeps->act; - for (; i < l_reldepsact; ++i) - if (list[i] == map) - goto out_check; - } - } - } - else - __rtld_lock_lock_recursive (GL(dl_load_lock)); - - /* The object is not yet in the dependency list. Before we add - it make sure just one more time the object we are about to - reference is still available. There is a brief period in - which the object could have been removed since we found the - definition. */ - runp = GL(dl_ns)[undef_map->l_ns]._ns_loaded; - while (runp != NULL && runp != map) - runp = runp->l_next; - - if (runp != NULL) - { - /* The object is still available. */ - - /* MAP could have been dlclosed, freed and then some other dlopened - library could have the same link_map pointer. */ - if (map->l_serial != serial) - goto out_check; - - /* Redo the NODELETE check, as when dl_load_lock wasn't held - yet this could have changed. */ - if ((map->l_flags_1 & DF_1_NODELETE) != 0) - goto out; - - /* If the object with the undefined reference cannot be removed ever - just make sure the same is true for the object which contains the - definition. */ - if (undef_map->l_type != lt_loaded - || (undef_map->l_flags_1 & DF_1_NODELETE) != 0) - { - map->l_flags_1 |= DF_1_NODELETE; - goto out; - } - - /* Add the reference now. */ - if (__glibc_unlikely (l_reldepsact >= undef_map->l_reldepsmax)) - { - /* Allocate more memory for the dependency list. Since this - can never happen during the startup phase we can use - `realloc'. */ - struct link_map_reldeps *newp; - unsigned int max - = undef_map->l_reldepsmax ? undef_map->l_reldepsmax * 2 : 10; - -#ifdef RTLD_PREPARE_FOREIGN_CALL - RTLD_PREPARE_FOREIGN_CALL; -#endif - - newp = malloc (sizeof (*newp) + max * sizeof (struct link_map *)); - if (newp == NULL) - { - /* If we didn't manage to allocate memory for the list this is - no fatal problem. We simply make sure the referenced object - cannot be unloaded. This is semantically the correct - behavior. */ - map->l_flags_1 |= DF_1_NODELETE; - goto out; - } - else - { - if (l_reldepsact) - memcpy (&newp->list[0], &undef_map->l_reldeps->list[0], - l_reldepsact * sizeof (struct link_map *)); - newp->list[l_reldepsact] = map; - newp->act = l_reldepsact + 1; - atomic_write_barrier (); - void *old = undef_map->l_reldeps; - undef_map->l_reldeps = newp; - undef_map->l_reldepsmax = max; - if (old) - _dl_scope_free (old); - } - } - else - { - undef_map->l_reldeps->list[l_reldepsact] = map; - atomic_write_barrier (); - undef_map->l_reldeps->act = l_reldepsact + 1; - } - - /* Display information if we are debugging. */ - if (__glibc_unlikely (GLRO(dl_debug_mask) & DL_DEBUG_FILES)) - _dl_debug_printf ("\ -\nfile=%s [%lu]; needed by %s [%lu] (relocation dependency)\n\n", - DSO_FILENAME (map->l_name), - map->l_ns, - DSO_FILENAME (undef_map->l_name), - undef_map->l_ns); - } - else - /* Whoa, that was bad luck. We have to search again. */ - result = -1; - - out: - /* Release the lock. */ - __rtld_lock_unlock_recursive (GL(dl_load_lock)); - - if (__glibc_unlikely (flags & DL_LOOKUP_GSCOPE_LOCK)) - THREAD_GSCOPE_SET_FLAG (); - - return result; - - out_check: - if (map->l_serial != serial) - result = -1; - goto out; -} - -static void -internal_function -_dl_debug_bindings (const char *undef_name, struct link_map *undef_map, - const ElfW(Sym) **ref, struct sym_val *value, - const struct r_found_version *version, int type_class, - int protected); - - -/* Search loaded objects' symbol tables for a definition of the symbol - UNDEF_NAME, perhaps with a requested version for the symbol. - - We must never have calls to the audit functions inside this function - or in any function which gets called. If this would happen the audit - code might create a thread which can throw off all the scope locking. */ -lookup_t -internal_function -_dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map, - const ElfW(Sym) **ref, - struct r_scope_elem *symbol_scope[], - const struct r_found_version *version, - int type_class, int flags, struct link_map *skip_map) -{ - const uint_fast32_t new_hash = dl_new_hash (undef_name); - unsigned long int old_hash = 0xffffffff; - struct sym_val current_value = { NULL, NULL }; - struct r_scope_elem **scope = symbol_scope; - - bump_num_relocations (); - - /* No other flag than DL_LOOKUP_ADD_DEPENDENCY or DL_LOOKUP_GSCOPE_LOCK - is allowed if we look up a versioned symbol. */ - assert (version == NULL - || (flags & ~(DL_LOOKUP_ADD_DEPENDENCY | DL_LOOKUP_GSCOPE_LOCK)) - == 0); - - size_t i = 0; - if (__glibc_unlikely (skip_map != NULL)) - /* Search the relevant loaded objects for a definition. */ - while ((*scope)->r_list[i] != skip_map) - ++i; - - /* Search the relevant loaded objects for a definition. */ - for (size_t start = i; *scope != NULL; start = 0, ++scope) - { - int res = do_lookup_x (undef_name, new_hash, &old_hash, *ref, - ¤t_value, *scope, start, version, flags, - skip_map, type_class, undef_map); - if (res > 0) - break; - - if (__glibc_unlikely (res < 0) && skip_map == NULL) - { - /* Oh, oh. The file named in the relocation entry does not - contain the needed symbol. This code is never reached - for unversioned lookups. */ - assert (version != NULL); - const char *reference_name = undef_map ? undef_map->l_name : ""; - - /* XXX We cannot translate the message. */ - _dl_signal_cerror (0, DSO_FILENAME (reference_name), - N_("relocation error"), - make_string ("symbol ", undef_name, ", version ", - version->name, - " not defined in file ", - version->filename, - " with link time reference", - res == -2 - ? " (no version symbols)" : "")); - *ref = NULL; - return 0; - } - } - - if (__glibc_unlikely (current_value.s == NULL)) - { - if ((*ref == NULL || ELFW(ST_BIND) ((*ref)->st_info) != STB_WEAK) - && !(GLRO(dl_debug_mask) & DL_DEBUG_UNUSED)) - { - /* We could find no value for a strong reference. */ - const char *reference_name = undef_map ? undef_map->l_name : ""; - const char *versionstr = version ? ", version " : ""; - const char *versionname = (version && version->name - ? version->name : ""); - - /* XXX We cannot translate the message. */ - _dl_signal_cerror (0, DSO_FILENAME (reference_name), - N_("symbol lookup error"), - make_string ("undefined symbol: ", undef_name, - versionstr, versionname)); - } - *ref = NULL; - return 0; - } - - int protected = (*ref - && ELFW(ST_VISIBILITY) ((*ref)->st_other) == STV_PROTECTED); - if (__glibc_unlikely (protected != 0)) - { - /* It is very tricky. We need to figure out what value to - return for the protected symbol. */ - if (type_class == ELF_RTYPE_CLASS_PLT) - { - if (current_value.s != NULL && current_value.m != undef_map) - { - current_value.s = *ref; - current_value.m = undef_map; - } - } - else - { - struct sym_val protected_value = { NULL, NULL }; - - for (scope = symbol_scope; *scope != NULL; i = 0, ++scope) - if (do_lookup_x (undef_name, new_hash, &old_hash, *ref, - &protected_value, *scope, i, version, flags, - skip_map, - (ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA - && ELFW(ST_TYPE) ((*ref)->st_info) == STT_OBJECT - && type_class == ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA) - ? ELF_RTYPE_CLASS_EXTERN_PROTECTED_DATA - : ELF_RTYPE_CLASS_PLT, NULL) != 0) - break; - - if (protected_value.s != NULL && protected_value.m != undef_map) - { - current_value.s = *ref; - current_value.m = undef_map; - } - } - } - - /* We have to check whether this would bind UNDEF_MAP to an object - in the global scope which was dynamically loaded. In this case - we have to prevent the latter from being unloaded unless the - UNDEF_MAP object is also unloaded. */ - if (__glibc_unlikely (current_value.m->l_type == lt_loaded) - /* Don't do this for explicit lookups as opposed to implicit - runtime lookups. */ - && (flags & DL_LOOKUP_ADD_DEPENDENCY) != 0 - /* Add UNDEF_MAP to the dependencies. */ - && add_dependency (undef_map, current_value.m, flags) < 0) - /* Something went wrong. Perhaps the object we tried to reference - was just removed. Try finding another definition. */ - return _dl_lookup_symbol_x (undef_name, undef_map, ref, - (flags & DL_LOOKUP_GSCOPE_LOCK) - ? undef_map->l_scope : symbol_scope, - version, type_class, flags, skip_map); - - /* The object is used. */ - if (__glibc_unlikely (current_value.m->l_used == 0)) - current_value.m->l_used = 1; - - if (__glibc_unlikely (GLRO(dl_debug_mask) - & (DL_DEBUG_BINDINGS|DL_DEBUG_PRELINK))) - _dl_debug_bindings (undef_name, undef_map, ref, - ¤t_value, version, type_class, protected); - - *ref = current_value.s; - return LOOKUP_VALUE (current_value.m); -} - - -/* Cache the location of MAP's hash table. */ - -void -internal_function -_dl_setup_hash (struct link_map *map) -{ - Elf_Symndx *hash; - - if (__glibc_likely (map->l_info[DT_ADDRTAGIDX (DT_GNU_HASH) + DT_NUM - + DT_THISPROCNUM + DT_VERSIONTAGNUM - + DT_EXTRANUM + DT_VALNUM] != NULL)) - { - Elf32_Word *hash32 - = (void *) D_PTR (map, l_info[DT_ADDRTAGIDX (DT_GNU_HASH) + DT_NUM - + DT_THISPROCNUM + DT_VERSIONTAGNUM - + DT_EXTRANUM + DT_VALNUM]); - map->l_nbuckets = *hash32++; - Elf32_Word symbias = *hash32++; - Elf32_Word bitmask_nwords = *hash32++; - /* Must be a power of two. */ - assert ((bitmask_nwords & (bitmask_nwords - 1)) == 0); - map->l_gnu_bitmask_idxbits = bitmask_nwords - 1; - map->l_gnu_shift = *hash32++; - - map->l_gnu_bitmask = (ElfW(Addr) *) hash32; - hash32 += __ELF_NATIVE_CLASS / 32 * bitmask_nwords; - - map->l_gnu_buckets = hash32; - hash32 += map->l_nbuckets; - map->l_gnu_chain_zero = hash32 - symbias; - return; - } - - if (!map->l_info[DT_HASH]) - return; - hash = (void *) D_PTR (map, l_info[DT_HASH]); - - map->l_nbuckets = *hash++; - /* Skip nchain. */ - hash++; - map->l_buckets = hash; - hash += map->l_nbuckets; - map->l_chain = hash; -} - - -static void -internal_function -_dl_debug_bindings (const char *undef_name, struct link_map *undef_map, - const ElfW(Sym) **ref, struct sym_val *value, - const struct r_found_version *version, int type_class, - int protected) -{ - const char *reference_name = undef_map->l_name; - - if (GLRO(dl_debug_mask) & DL_DEBUG_BINDINGS) - { - _dl_debug_printf ("binding file %s [%lu] to %s [%lu]: %s symbol `%s'", - DSO_FILENAME (reference_name), - undef_map->l_ns, - DSO_FILENAME (value->m->l_name), - value->m->l_ns, - protected ? "protected" : "normal", undef_name); - if (version) - _dl_debug_printf_c (" [%s]\n", version->name); - else - _dl_debug_printf_c ("\n"); - } -#ifdef SHARED - if (GLRO(dl_debug_mask) & DL_DEBUG_PRELINK) - { -/* ELF_RTYPE_CLASS_XXX must match RTYPE_CLASS_XXX used by prelink with - LD_TRACE_PRELINKING. */ -#define RTYPE_CLASS_VALID 8 -#define RTYPE_CLASS_PLT (8|1) -#define RTYPE_CLASS_COPY (8|2) -#define RTYPE_CLASS_TLS (8|4) -#if ELF_RTYPE_CLASS_PLT != 0 && ELF_RTYPE_CLASS_PLT != 1 -# error ELF_RTYPE_CLASS_PLT must be 0 or 1! -#endif -#if ELF_RTYPE_CLASS_COPY != 0 && ELF_RTYPE_CLASS_COPY != 2 -# error ELF_RTYPE_CLASS_COPY must be 0 or 2! -#endif - int conflict = 0; - struct sym_val val = { NULL, NULL }; - - if ((GLRO(dl_trace_prelink_map) == NULL - || GLRO(dl_trace_prelink_map) == GL(dl_ns)[LM_ID_BASE]._ns_loaded) - && undef_map != GL(dl_ns)[LM_ID_BASE]._ns_loaded) - { - const uint_fast32_t new_hash = dl_new_hash (undef_name); - unsigned long int old_hash = 0xffffffff; - struct unique_sym *saved_entries - = GL(dl_ns)[LM_ID_BASE]._ns_unique_sym_table.entries; - - GL(dl_ns)[LM_ID_BASE]._ns_unique_sym_table.entries = NULL; - do_lookup_x (undef_name, new_hash, &old_hash, *ref, &val, - undef_map->l_local_scope[0], 0, version, 0, NULL, - type_class, undef_map); - if (val.s != value->s || val.m != value->m) - conflict = 1; - else if (__glibc_unlikely (undef_map->l_symbolic_in_local_scope) - && val.s - && __glibc_unlikely (ELFW(ST_BIND) (val.s->st_info) - == STB_GNU_UNIQUE)) - { - /* If it is STB_GNU_UNIQUE and undef_map's l_local_scope - contains any DT_SYMBOLIC libraries, unfortunately there - can be conflicts even if the above is equal. As symbol - resolution goes from the last library to the first and - if a STB_GNU_UNIQUE symbol is found in some late DT_SYMBOLIC - library, it would be the one that is looked up. */ - struct sym_val val2 = { NULL, NULL }; - size_t n; - struct r_scope_elem *scope = undef_map->l_local_scope[0]; - - for (n = 0; n < scope->r_nlist; n++) - if (scope->r_list[n] == val.m) - break; - - for (n++; n < scope->r_nlist; n++) - if (scope->r_list[n]->l_info[DT_SYMBOLIC] != NULL - && do_lookup_x (undef_name, new_hash, &old_hash, *ref, - &val2, - &scope->r_list[n]->l_symbolic_searchlist, - 0, version, 0, NULL, type_class, - undef_map) > 0) - { - conflict = 1; - val = val2; - break; - } - } - GL(dl_ns)[LM_ID_BASE]._ns_unique_sym_table.entries = saved_entries; - } - - if (value->s) - { - /* Keep only ELF_RTYPE_CLASS_PLT and ELF_RTYPE_CLASS_COPY - bits since since prelink only uses them. */ - type_class &= ELF_RTYPE_CLASS_PLT | ELF_RTYPE_CLASS_COPY; - if (__glibc_unlikely (ELFW(ST_TYPE) (value->s->st_info) - == STT_TLS)) - /* Clear the RTYPE_CLASS_VALID bit in RTYPE_CLASS_TLS. */ - type_class = RTYPE_CLASS_TLS & ~RTYPE_CLASS_VALID; - else if (__glibc_unlikely (ELFW(ST_TYPE) (value->s->st_info) - == STT_GNU_IFUNC)) - /* Set the RTYPE_CLASS_VALID bit. */ - type_class |= RTYPE_CLASS_VALID; - } - - if (conflict - || GLRO(dl_trace_prelink_map) == undef_map - || GLRO(dl_trace_prelink_map) == NULL - || type_class >= 4) - { - _dl_printf ("%s 0x%0*Zx 0x%0*Zx -> 0x%0*Zx 0x%0*Zx ", - conflict ? "conflict" : "lookup", - (int) sizeof (ElfW(Addr)) * 2, - (size_t) undef_map->l_map_start, - (int) sizeof (ElfW(Addr)) * 2, - (size_t) (((ElfW(Addr)) *ref) - undef_map->l_map_start), - (int) sizeof (ElfW(Addr)) * 2, - (size_t) (value->s ? value->m->l_map_start : 0), - (int) sizeof (ElfW(Addr)) * 2, - (size_t) (value->s ? value->s->st_value : 0)); - - if (conflict) - _dl_printf ("x 0x%0*Zx 0x%0*Zx ", - (int) sizeof (ElfW(Addr)) * 2, - (size_t) (val.s ? val.m->l_map_start : 0), - (int) sizeof (ElfW(Addr)) * 2, - (size_t) (val.s ? val.s->st_value : 0)); - - _dl_printf ("/%x %s\n", type_class, undef_name); - } - } -#endif -} |